Speech Tracking in Complex Auditory Scenes with Differentiated In- and Out-Field-Of-View Processing in Hearing Aids.

In naturalistic auditory scenes, relevant information is rarely concentrated at a single location, but rather unpredictably scattered in- and out-field-of-view (in-/out-FOV). Although the parsing of a complex auditory scene is a fairly simple job for a healthy human auditory system, the uncertainty represents a major issue in the development of effective hearing aid (HA) processing strategies. Whereas traditional omnidirectional microphones (OM) amplify the complete auditory scene without enhancing signal-to-noise-ratio (SNR) between in- and out-FOV streams, directional microphones (DM) may greatly increase SNR at the cost of preventing HA users to perceive out-FOV information. The present study compares the conventional OM and DM HA settings to a split processing (SP) scheme differentiating between in- and out-FOV processing. We recorded electroencephalographic data of ten young, normal-hearing listeners who solved a cocktail-party-scenario-paradigm with continuous auditory streams and analyzed neural tracking of speech with a stimulus reconstruction (SR) approach. While results for all settings exhibited significantly higher SR accuracies for attended in-FOV than unattended out-FOV streams, there were distinct differences between settings. In-FOV SR performance was dominated by DM and SP and out-FOV SR accuracies were significantly higher for SP compared to OM and DM. Our results demonstrate the potential of a SP approach to combine the advantages of traditional OM and DM settings without introduction of significant compromises.

Minimum Audible Angles Measured with Simulated Normally-Sized and Oversized Pinnas for Normal-Hearing and Hearing-Impaired Test Subjects.

The human pinna introduces spatial acoustic cues in terms of direction-dependent spectral patterns that shape the incoming sound. These cues are specifically useful for localization in the vertical dimension. Pinna cues exist at frequencies above approximately 5 kHz, a frequency range where people with hearing loss typically have their highest hearing thresholds. Since increased thresholds often are accompanied by reduced frequency resolution, there are good reasons to believe that many people with hearing loss are unable to discriminate these subtle spectral pinna--cue details, even if the relevant frequency region is amplified by hearing aids.One potential solution to this problem is to provide hearing-aid users with artificially enhanced pinna cues-as if they were listening through oversized pinnas. In the present study, it was tested whether test subjects were better at discriminating spectral patterns similar to enlarged-pinna cues. The enlarged-pinna patterns were created by transposing (T) generic normal-sized pinna cues (N) one octave down, or by using the approach (W) suggested by Naylor and Weinrich (System and method for generating auditory spatial cues, United States Patent, 2011). The experiment was cast as a determination of simulated minimum audible angle (MAA) in the median saggital plane. 13 test subjects with sloping hearing loss and 11 normal-hearing test subjects participated. The normal-hearing test subjects showed similar discrimination performance with the T, W, and N-type simulated pinna cues, as expected. However, the results for the hearing-impaired test subjects showed only marginally lower MAAs with the W and T-cues compared to the N-cues, while the overall discrimination thresholds were much higher for the hearing-impaired compared to the normal-hearing test subjects.

Air ambulance and hospital services for critically ill and injured in Greenland, Iceland and the Faroe Islands: how can we improve?

The Nordic Atlantic Cooperation (NORA) is an intergovernmental organization under the auspices of the Nordic Council of Ministers. The NORA region comprises Greenland, Iceland, Faroe Islands and western coastal areas of Norway. Historical, cultural and institutional links bind these nations together in multiple ways, and regional co-operation has in recent years become a focus of interest. This commentary addresses air medical services (AMSs) and available advanced hospital services in the 3 smallest NORA countries challenged sparse populations, hereafter referred to as the region. It seems likely that strengthened regional co-operation can help these countries to address common challenges within health care by exchanging know-how and best practices, pooling resources and improving the efficiency of care delivery. The 4 largest hospitals in the region, Dronning Ingrids Hospital in Nuuk (Greenland), Landspítali in Reykjavík and Sjúkrahúsið á Akureyri, (both in Iceland) and Landssjúkrahúsið Tórshavn on the Faroe Islands, have therefore undertaken the project Network for patient transport in the North-West Atlantic (in Danish: Netværk for patienttransport i Vest-Norden). The goal of the project, and of this article, is to exchange information and provide an overview of current AMSs and access to acute hospital care for severely ill or injured patients in the 3 participating countries. Of equal importance is the intention to highlight the need for increased regional co-operation to optimize use of limited resources in the provision of health care services.